"Caecu" is pronounced "kay, ek ooo", and is shortened from the Latin "Caecus", meaning blind.

The only idea I had in my head when starting this was an alien raptor-like pack predator, so this guy was pretty spontaneous.

It navigates and hunts using a combination of echolocation and infrared sensitive pit receptors which allows them to see the radiated heat of warm blooded creatures.

The fan on the end of their tail can fold down or erect to be flushed or drained of blood, allowing them to send heat coded messages to one another. I guess it'd also be somewhat useful as a rudder while running. It'd flush red when excited or on the trail of prey, then they'd either proceed to chase their victim down or plan out ambushes, in which they take turns bombarding the prey with blasts of sonar while others leap onto and slash into the victim. They're also great endurance runners, and like to tire larger more dangerous prey with prolonged chases before attacking.

Cool critter! I like your description as well- this is something that I can imagine Riddick having to deal with, ha ha. Do these guys live on a planet without much light? It's hard to imagine an animal that would not find eyes useful, even though the eye-dea of an eyeless creature that hunts using sonar or heat is so fascinating to creature designers.

Yeah, maybe if sandstorms were a constant occurrence he wouldn't have much need for sight, but realistically some sort of rudimentary vision would be present in even the dimmest situations. Mostly for this guy it was all aesthetics. But thank you!